1. Field of the Invention
The present invention relates to a detergent composition for removing resinous stains, and more particularly to a detergent composition exhibiting excellent removability against difficult-to-remove resinous stains adhered to surfaces of hard materials, such as plastic lens resins, tackifiers, paints, ink cured products, adhesives for temporary fixing, fixing agents, bonding agents, sealing agents, binders, and protective films. In addition, the present invention relates to a method for removing resinous stains, more particular to a method for removing resinous stains which are ascribed to one or more members selected from plastic lens resins, adhesives, and tackifiers adhered to plastic lens or adhered to glass molds, jigs and tools usable in the production process of the plastic lens.
2. Discussion of the Related Art
The resinous stains, which are ascribed to one or more members selected from plastic lens resins, adhesives, tackifiers, and the like, adhered to optical parts, such as plastic lens, or resinous materials, and to glass molds, jigs and tools usable in the production processes of the plastic lens; paints, such as body coatings upon color changes in automobile production, paints adhered to jigs for painting, paints for automobile bumpers for recycling and reuse, paints for constructions, such as sash made of aluminum and buildings; ink cured products adhered to printing machines during printing, such as gravure, and the like; resists using producing electronic parts or for metal process products, such as semiconductors and lead-frames; resins such as adhesives for temporary fixing, fixing agents, bonding agents, sealing agents, and the like, which are adhered to semiconductor and crystalline materials such as silicon, gallium arsenide, and gallium phosphide, electronic part-related materials such as crystals, quartz, glass, and piezoelectric element, magnetic materials such as ferrite and samarium cobalt, magnetic member materials such as magnetic heads, electronic parts such as chip-type electronic parts, electric parts or precision machine parts, such as liquid crystal color filters and printed wiring boards, or adhered to jigs and tools usable in the processing and production processes thereof; and resins, such as binders, paints, and protective films removed during recycling of the above parts, are firmly adhered or bonded to surfaces of hard materials and the resinous stains themselves are ascribed to resins having high molecular weights, thereby making it extremely difficult to conduct cleaning with chemicals utilizing actions such as dissolution swelling, softening, flecking, and peeling. In particular, the resinous stains ascribed to plastic lens and adhered to glass molds during the production of the plastic lens have extremely high molecular weights, so that it is considered to be one of the most difficult-to-remove resinous stains.
The resins usable for plastic lens include resins obtained by radical polymerization of diethylene glycol bis(allyl carbonate) (ADC), methacrylic resins, copolymer resins of fumaric acid ester-allyl monomer, triazine cyclic acrylic resins, polycarbonate resins, bromine-containing resins, urethane resins, sulfur-containing urethane resins, thioether-ester resins, and the like.
A general method for producing plastic lens comprises pouring monomeric forming materials in a cast mold formed by cyclic packing (gasket) or tape comprising two glass molds and a synthetic resin wrapping around the peripheral portion of the glass molds, and subsequently polymerizing the monomeric components with heating. After the polymerization process, the cyclic packing or tape is removed from the cast mold, and the plastic lens resins are taken out of the glass molds. Since resulting plastic lens have a non-uniform shape in the peripheral portions thereof, the peripheral portions are reshaped, and subsequently chamfering of the edge portion is conducted. The chamfered plastic lens are conveyed to a vessel for the cleaning process.
After removing the oligomeric stains and the polymeric stains adhered to lens surfaces during removal of the packing from the molds, the polymer powder adhered during peripheral reshaping and chamfering, unreacted monomers remaining on lens surfaces, powdery dusts in the atmosphere, and the like, are subjected to cleaning, and the cleaned plastic lens are subjected to surface treatments such as dyeing, hard coat, reflection-preventive coat and aqua coat to prepare a commercial product thereof.
Since the glass molds usable in the production of the plastic lens are extremely expensive, the glass molds are repeatedly used for several hundred times to several thousand times as long as they do not crack. Therefore, it is necessary to remove oligomeric or polymeric stains ascribed to the starting materials of the plastic lens dropping out from the glass molds when pouring the monomeric components. Unless the glass molds are clean, it would be impossible to produce high-quality plastic lens with smooth surfaces, and such glass molds which cannot produce smooth surface plastic lens must be disposed as wastes, thereby making it extremely economically disadvantageous.
Conventionally, in order to remove oligomeric or polymeric stains formed on the glass molds usable in the production of the plastic lens, alkaline detergents, having sodium hydroxide or potassium hydroxide as a main component, and methylene chloride have been used.
Among the conventionally used detergents, the alkaline detergent does not give sufficient removability, requiring a long period of time to completely remove stains. In addition, it is necessary remove the stains by hand. In addition, the methylene chloride by itself is also deficient in removability of dirt stains, so that in some cases the methylene chloride is used together with the alkaline detergent. Moreover, since it is possible that the methylene chloride is a carcinogen, strict regulations are in place to prevent its leakage into waste water or the atmosphere. Therefore, the reduction and banning of its use have been in demand.
In the process of removing of oligomeric or polymeric stains formed on the plastic lens or the glass molds, Japanese Patent Laid-Open No. Hei 5-269448, for instance, discloses a process of cleaning plastic lens and glass molds to which stains are adhered comprising dispersing monomers in a solvent, subjecting the stains to an ultrasonic cleaning, liquid or vaporous shower cleaning, and stir-cleaning. However, in this cleaning process, the larger the molecular weight of the resinous stains, the more period of time is necessitated in dissolution and dispersion, so that sufficient removability cannot be achieved.
In addition, a cleaning process of other resinous stains are disclosed in Japanese Patent Laid-Open No. Hei 4-359257 pertaining to a peeling solution for removing an alkali-developing type photoresist film, comprising a peeling solution for etching a resist film comprising an alkali metal hydroxide or an alkali metal silicate, a benzyl alcohol, and water as essential components for photoetching. However, this peeling liquid is applicable to only alkali-developing type photoresist films, and it cannot be applied to resists conventionally peeled with chlorine-containing solvents, having higher degrees of polymerization.
Accordingly, an object of the present invention is to provide a detergent composition having excellent removability against resinous stains and excellent safety.
Another object of the present invention is to provide a method for removing resinous stains using the detergent composition.
These and other objects of the present invention will be apparent from the following description.